1. Field of the Invention
The present invention generally relates to a micro-fluidic heating system applied in a micro automatic analysis system, and more particularly, to a micro-fluidic heating system that can be fabricated with a low cost and can be used as disposable applications and has fast heating and cooling speeds.
2. Discussion of Related Art
In general, a micro automatic analysis system such as a bio sensor, a bio chip, a High Throughput Screening (HTS) system, and a combinatory chemistry system requires a micro-fluidic control system having a heating function. Such a micro-fluidic control system requires a function of heating or cooling a single chamber or a plurality of chambers within the system in a short time.
To that end, methods for forming multi-layered flow patterns and integrating a plurality of chambers and heaters within a micro-fluidic control element have been researched (See U.S. Pat. No. 6,572,830; 3 Jun. 2003). However, when the heater is integrated in the micro-fluidic control element, the micro pattern for forming the heater and a temperature sensor should be formed within the element and its value should be compensated, which requires a lower portion of the chamber of the micro-fluidic control element to be formed as a membrane so as to enhance thermal transfer performance. As a result, a processing cost disadvantageously becomes increased.
A micro-fluidic control system is also proposed, which includes a micro-fluidic control element and a main body that are integrated together while having separated heating function (See Liu et al., “DNA amplification and hybridization assys in integrated plastic monolithic devices”, Analytical chemistry, Vol. 74, No. 13, pp. 3063-3070). This system uses a peltier element having a high thermal mass as a heater, wherein the lower portion of the chamber of the micro-fluidic control element is made thick to have a thickness of 200 μm, which causes the thermal transfer speed to be decreased to degrees of 7.9° C./s in heating and 4.6° C./s in cooling.
A micro-fluidic control element comprising a membrane type heater and a single chamber has been proposed (See Lee et al., “Submicroliter volume PCR chip with fast thermal response and very low power consumption”, Proc. Of MicroTAS 2003, pp. 187-190, 2003. 10. 5). The micro-fluidic control element has a small heat transfer coefficient and uses a thin membrane of about 2 μm, so that it has a fast speed for heating and cooling to a degree of 60° C./s to 80° C./s. However, as the heating function is included in the micro-fluidic element for single use, which causes its fabrication process to be complicated.
An assembly has been proposed, wherein the heater and the single chamber are separated, and a contact portion on the side of the single chamber in contact with the heater is formed as a film, and the heater in a main body is formed as a thin thermal plate to enhance thermal transfer efficiency (See WO Publication No. 98/38487(1998. 9. 3), Chang Ronald et al., “Heat exchange, optically interrogated chemical reaction assembly”). In such a structure, the whole portion in contact with the micro-fluidic control element of the main body is used as a thermal plate, which fails to locally heat or cool only the chamber in a case of integrated micro-fluidic control element. Furthermore, the thermal plate is fabricated by a conventional machine processing method, so that the element has an increased thermal mass due to the thickness and size of its thermal plate, which fails to have fast heating and cooling speeds compared to the element fabricated by a surface micromachining process.